Optimizing your image with Pixlr on

Optimizing your image with Pixlr on-line photo editor
Nick Dvoracek•dvoracek@uwosh.edu
In a web browser,
go to http://pixlr.com/editor/
Click Open image from computer
That will open a standard file dialogue
box on your computer. Browse to
find your original scan or camera file,
select it and click Open.
This will open your file in the Pixlr Photo Editor.
Menu bar
Tool palette
Layers
Zoom control
History
Rotating your image
If your image is not in the correct
orientation, under the Image
menu, select the appropriate
Rotate command.
Improving the overall appearance of your image.
From the Adjustments menu, select Levels.
This will bring up a graph of the distribution of tones
in your image, which has three adjustment controls at
the bottom of the graph, which can reset the blackest
thing in the image, the whitest thing in the image, and
can adjust the distributions of the middle tones.This is
a floating window—you probably want to grab it by
its title bar and move it out of the way of the image.
Every image will have a different distribution and will
need different adjustments (or maybe none at all).
Black
point
Mid
point
White
point
With most images, drag the black slider to the blackest part of the
graph and the white slider to the whitest part of the graph. Then move
the middle point back and forth until you think the image looks best.
Moving the mid point to the right darkens the image and moving it to
the left. lightens the image.
Black point Adjusted Adjusted
needed no Mid point White point
adjustment
in this image.
In this image, the camera’s exposure metering was fooled by the
extremely bright sky, making the center of interest extremely
underexposed. In order to make the main interest of the image
correctly rendered, I had to move the white point quite a bit to the left,
which eliminated any detail in the clouds
Every problem exposure is going to have it’s own needs for adjustment.
Take some time and play around with these adjustments.
When you are satisified with the new appearance, click OK.
If you’re not happy after clicking OK, rather than selecting the Levels
command again and applying more adjustments, go back a step
in the History window and then try again from the original image.
Repeating the levels command can reduce the amount of color
information to the point you might have noticable banding where
shades transition from one level to another.
If you’re not sure, you can save the image (see Saving the Image later on), try adjusting levels again, and if you
like it better, save that version. If you decide you liked your first adjustment better, you’ve got it saved. If you’re not
sure, you can give the file a different name each time you save it, and compare them later.
Adjusting areas of your photograph with the Burning and Dodging tools
Tools exist in Pixlr to lighten or darken just certain areas in your Image. Based on traditional darkroom techniques
they are known as Dodging for lightening an area, and Burning In for darkening an area.
You can adjust the size of the area affected (Brush), how strong an effect it will have (Exposure), and whether
the tool you are using has a soft or hard edge. This is a bit of an acquired skill, and it’s easy to make an image look
unnatural. with obviously adjusted areas. Start with low levels of exposure and use as soft-edged a tool as possible
In this image, I started with the shot that had the normally exposed sky but very underexposed figure..
I carefully dodged the face and some of the shoulders to bring it more in the normal range while keeping the
texture in the sky. Notice how different the impact of the image is compared to the version on the previous page
which was simply lightened
Dodging
tool
Burning
tool
This usually requires a lot of
trial and error. Remember the
Undo command and the History
window to go back and try again.
Brush Pallete
You can pick the size,
shape and hardness
off the menu or specify
Diameter, (the size of
the tool), Spacing, (sort
of skips the tool in spots,
normally keep this at 1),
and Hardness (usually
you want this at 0)
Retouching with the Clone tool
It’s possible to remove flaws such as stray hairs and zits with the Clone tool. The Clone tool allows
you to paint over part of an image with another part of the image.
Typically you want to use as small a brush as necessary for what you’re retouching. You select the
area from which to copy, generally right next to the flaw you want to remove, by holding down
Cntrl and clicking (Command-click on the Macintosh), and then click and drag to paint out the flaw.
The spot that’s being sampled and the spot that is being painted stay aligned, so you constantly
have to adjust where you’re selecting as you move around. Randomly varying the spot thats being
sampled as you go along can help blend in the effect. Again, kind of an acquired skill.
In the screen capture below, I’m retouching the photo on the left to remove some of the stray hair.
The original is on the right for comparison. Note that I’ve zoomed in quite a bit to get a good look
at what I’m doing.
The spot that is The spot that’s
being painted being sampled
Cropping the image
Sometimes you want to use just part of a photograph, or to eliminate a distracting element at the edge.
You can use the Crop tool. (again based on tradition methods. The icon represents a traditional tool for
previewing cropped images)
Select the Crop tool from
the top left of the tool box.
The cursor will appear as a
cross hairs with the cropping
squares icon next to.
Click and drag out the area
you wish to retain.
Note that the
cropped image
is much smaller
in number of
pixels, and
therefore can’t
be enlarged as
much
When you release the mouse button, lines
indicating the selected area appear with blue
handles in the corners. Placing the cursor in
one of these handles will change it to a two
headed arrow and will allow you to adjust the
selected area.
Double clicking inside the selected area
will complete the crop.
Making your image the right size for your purpose
If you’re intending to print, it’s probably best to keep all the data you capture with the camera or scanner.. To
get optimum quality from a photo printer you need about 200 dots per inch. That is if you’re making a 4 x 6
print it should be at least 800 x 1200 pixels. For an 8 x 10 inch enlargement you’d need 1600 x 2000 pixels.
This is well within the range of even cell phone cameras.
For on-screen display in a program like PowerPoint or Keynote, the biggest you really need is about a
1000 pixels wide for a screen filling image. Just using the image as it came from your camera can make your
presentation file size much bigger than necessary.
Some web applications require you to resize your image before you put it on the web or it may appear larger
than screen itself. The most common size moniter is 1240 pixels wide so for whatever portion of the screen
you want to fill, reduce to the file to that proportion of 1240. If you want it to fill half the screen, you’d want
620 pixels.
After reducing the number of pixels, remember to save under a different file name to retain your full size image
in case you need it later on..
From the Image menu, select
Image Size
Saving your file
From the Pixlr File menu,
select Save.
Set the most critical dimension, if
Constrain proportions is checked
(you really want it checked) the
other dimension will resize properly
automatically.
In the Name field, to make
sure you don’t overwrite your
original image file, change the
name slightly.
From the Format menu, make
sure JPEG is selected.
Drag the Quality slider to the
left to save file space. If you
want to archive a high quality
image, drag to the right to
maximize image quality.
Most images will show no
decrease in quality down to
about a Quality setting of 30
Clicking OK will open a standard file dialogue box. Take note of where you’re saving the file and click Save,.
There are many other adjustments in Pixlr such as adjusting color balance and using layers for combining
images from mulitple files and labeling images.